Microelectronic devices are continually becoming smaller, and the circuit density, operating speeds and switching rates are continually increasing. This trend has impacted the design and manufacture of a variety of components that support the operation of microelectronic devices, such as voltage regulation devices, inductors, capacitors, and the like. In regard to capacitors, the decreased size and increased speed trend has amplified issues with respect to the inductance of capacitors, which have not previously been a critical concern.
Capacitors can be used for a variety of reasons, including as a means to store energy for use by microelectronic devices during periods of non-steady state or transient current demands, or to manage noise problems that occur in microelectronic circuit applications. Inductance is a capacitor limitation that is becoming more critical as microelectronic devices get smaller and faster. The higher the inductance, the slower the capacitor, as a power source, responds to a transient current demand. Accordingly, it is one goal of the industry to reduce inductance in capacitors, so as to allow them to timely respond to the energy demands as required by a microelectronic device (e.g. within the first few cycles).
FIG. 1 is a side view of an example of a capacitor of the prior art design. Capacitors commonly consist of a first conductive plate 10 and a second conductive plate 12. The first conductive plate 10 is electrically interconnected to a plurality of conductive first electrodes 14. The second conductive plate 12 is electrically interconnected to a plurality of conductive second electrodes 16. Dielectric material 18 is dispersed between the plurality of first electrodes and the plurality of second electrodes. The dielectric material 18 can be any nonconductive material, including, but not limited to air, aluminum oxide, ceramics, mica, and the like.
The charge or polarity of the first conductive plate 10 and the first electrodes 14 is opposite to the charge of the second conductive plate 12 and the second electrodes 16, such that the electrical energy of the charged system then is stored in the polarized dielectric. First conductive plate 10 terminates at first terminal 20 and second conductive plate 12 terminates at second terminal 22. First and second terminals 20 and 22 can then be electrically interconnected to a conductive path, such as a power trace in a printed circuit board that electrically interconnects a power source with a microelectronic device (not shown).
Inductance is dependent on factors such as the separation distance between first and second electrodes 14 and 16, as well as the first and second conductive plates 10 and 14. Generally, inductance is directly proportional to the distance between the oppositely charged surfaces, i.e. first and second electrodes 14 and 16 and first and second conductive plates 10 and 14, show by terminal distance arrow 24. As such, industry has attempted to reduce both distances, in order to reduce inductance. As new dielectric materials 18 with higher dielectric constants are developed, the distance between the conductive plates may be reduced.
New configurations and methods for reducing the distance between the conductive surfaces 10 and 12 are needed to reduce inductance of capacitors, which will increase the capacitor response time to the energy demands of the smaller, yet higher speed microelectronic devices.